NSURLSession代表与完成Handler [英] NSURLSession delegate vs. completionHandler

问题描述

我一直使用完成处理程序。使用 NSURLConnection ，现在使用 NSURLSession 。这是导致我的代码真的不整洁，特别是我在请求中请求请求。

我想尝试使用代理在 NSURLSession 来实现我用 NSURLConnection 做的事情。

所以我创建了一个 NSURLSession ，并创建了一个 dataTask ：

  NSURLSessionDataTask * dataTask = [overallSession dataTaskWithURL：url 
 completionHandler：^（NSData * data，NSURLResponse * response ，NSError * error）{
 if（error == nil）
 {
 NSString * text = [[NSString alloc] initWithData：data encoding：NSUTF8StringEncoding]; 
 NSLog（@Data =％@，text）; 
} 
 
}]; 
 
 [dataTask resume]; 
  

现在我有一个 completionHandler 响应，我如何切换到代理来管理响应和数据？我可以从这个代理中添加另一个 dataTask 吗？使用这个 dataTask 创建并放入会话的cookie？

解决方案

如果要添加自定义委托类，则需要至少实现 NSURLSessionDataDelegate 和 NSURLSessionTaskDelegate 协议。

使用以下方法：

NSURLSessionDataDelegate - 获取请求的连续状态

（NSURLSession *）会话dataTask：（NSURLSessionDataTask *）dataTask didReceiveResponse :( NSURLResponse *）响应
completionHandler：（void（ ^）（NSURLSessionResponseDisposition处置））completionHandler {

receivedData = nil; receivedData = [[NSMutableData alloc] init];
[receivedData setLength：0];

completionHandler（NSURLSessionResponseAllow）;
}

NSURLSessionDataDelegate

<$ p $（$）$（$）$（$）$（$）$（$）$（$）$（$）$ ：数据];
}

NSURLSessionTaskDelegate

<$ p $（$）$（$）$（$）$（$）$（$）$ {code $ c $ $ b //处理错误
}
else {
NSDictionary * response =（NSDictionary *）[NSJSONSerialization JSONObjectWithData：receivedData选项：kNilOptions错误：& tempError];
//执行NSDictionary响应的操作
}

如果你想将代理代码（中间层）从您的呼叫类中分离出来（通常它的良好做法有单独的类/网络呼叫层），NSURLSession的代表必须是： -

  NSURLSession * session = [NSURLSession sessionWithConfiguration：sessionConfig delegate：myCustomDelegateClass delegateQueue：nil]; 
  

参考链接：

1. NSURLSession类参考


2. iOS NSURLSession示例（HTTP GET，POST，Background Downlads）


3. 从NSURLConnection到NSURLSession

I've always used completion handlers. With NSURLConnection and now with NSURLSession. It's led to my code being really untidy, especially I have request within request within request.

I wanted to try using delegates in NSURLSession to implement something I've done untidily with NSURLConnection.

So I created a NSURLSession, and created a dataTask:

NSURLSessionDataTask *dataTask = [overallSession dataTaskWithURL:url
                                                  completionHandler:^(NSData *data, NSURLResponse *response, NSError *error) {
                                                      if(error == nil)
                                                      {
                                                          NSString * text = [[NSString alloc] initWithData: data encoding: NSUTF8StringEncoding];
                                                          NSLog(@"Data = %@",text);
                                                      }

                                                  }];

    [dataTask resume];

Right now I have a completionHandler for the response, how would I switch to delegates to manage the response and data? And can I add another dataTask from the delegate of this one? Using the cookies that this dataTask created and placed into the session?

解决方案

If you want to add a custom delegate class, you need to implement the NSURLSessionDataDelegate and NSURLSessionTaskDelegate protocols at the minimum.

With the methods:

NSURLSessionDataDelegate - get continuous status of your request

 - (void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask didReceiveResponse:(NSURLResponse *)response
 completionHandler:(void (^)(NSURLSessionResponseDisposition disposition))completionHandler {

    receivedData=nil; receivedData=[[NSMutableData alloc] init];
    [receivedData setLength:0];

    completionHandler(NSURLSessionResponseAllow);
}

NSURLSessionDataDelegate

-(void)URLSession:(NSURLSession *)session dataTask:(NSURLSessionDataTask *)dataTask
   didReceiveData:(NSData *)data {

    [receivedData appendData:data];
}

NSURLSessionTaskDelegate

 - (void)URLSession:(NSURLSession *)session task:(NSURLSessionTask *)task
didCompleteWithError:(NSError *)error {
 if (error) {
  // Handle error
 }
else {
   NSDictionary* response=(NSDictionary*)[NSJSONSerialization JSONObjectWithData:receivedData options:kNilOptions error:&tempError];
    // perform operations for the  NSDictionary response
}

If you want to separate the delegate code (middle layer) from your calling class (generally its good practice to have separate class/layer for network calls), the delegate of NSURLSession has to be :-

NSURLSession *session=[NSURLSession sessionWithConfiguration:sessionConfig delegate:myCustomDelegateClass delegateQueue:nil];

Ref Links:

1. NSURLSession Class Reference
2. iOS NSURLSession Example (HTTP GET, POST, Background Downlads )
3. From NSURLConnection to NSURLSession

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